Dolichols are unusual long-chain alcohols found in all mammalian liver. The functions of these compounds have been unknown until recent years, but it is now known that they participate in the synthesis of complex glycoproteins in the tissues of all animals, including man. the role of these compounds in the synthesis of human histocompatibility antigens has been studied in our laboratory. These antigens are surface glycoproteins present on all cells which determine the ability of animals to accept or reject a tissue graft (such as a heart, kidney, or skin) from another animal of the same species. At the same time, as a model for the mechanism by which animals synthesize glycoproteins, we have been studying the mechanism of synthesis of very unusual glycoprotein, found in the cell envelope of Halobacteria, bacteria which live at high salt concentrations, such as are found in the Great Salt Lake or Dead Sea. The Halobacteria glycoprotein is a unique example of this type of compound found in the microbial world. The ease with which these microorganisms can be manipulated make them an excellent model for studying the processes by which glycoproteins are assembled. Knowledge of the mechanisms of the synthesis of glycoproteins in animals could eventually be used in the manipulation of human transplantation. BIBLIOGRAPHIC REFERENCE: Mescher, M.F. and Strominger, J.L. Purification and characterization of a prokaryotic glycoprotein from the cell envelope of Halobacterium salinarium. J. Biol. Chem. 251: 2005-2014 (1976).